Shelf unit



FIG. 1 is a front perspective view of a shelf unit showing my new design;

FIG. 2 is a left side elevational view thereof, the right side being identical in appearance;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a front perspective view of a second embodiment of the shelf unit shown in FIG. 1;

FIG. 5 is a left side elevational view thereof, the right side being identical in appearance; and

FIG. 6 is a rear elevational view thereof. 

The ornamental design for a shelf unit, as shown and described. 